Kiln with overlying beds for drying, burning and sintering of granular and/or sludge-type material

ABSTRACT

A kiln with overlying beds for drying, burning and sintering granular and/or sludge-type material is provided with a centrally arranged vertical hollow rotatable shaft having outwardly extending raking arms thereon for distributing the material to be treated over the beds. The material to be treated is fed above the kiln into a fixed vertical pipe which extends into the upper end of a vertical distribution pipe arranged within the rotatable hollow shaft. The lower end of this vertical pipe is deflected laterally and passes through the wall of the vertical shaft and delivers the material to be treated to the uppermost bed while rotating with the hollow shaft. From the uppermost bed the material descends to the next lower beds through suitable apertures in the periphery and the center portions of the beds until it is finally discharged from the lower end of the kiln.

United States Patent [1 1 Kryczun et al.

[ KILN WITII OVERLYING BEDS FOR DRYING, BURNING AND SINTERING OF GRANULAR AND/OR SLUDGE-TYPE MATERIAL [75] Inventors: Alfred Kryczun; Theo Manshausen,

both of Cologne, Germany [73] Assignee: Klockner-llumboldt-Deutz Aktiengeselischaft, Cologne. Germany 22 Filed: Aug. 9, 1971 21 Appl.No.: 170,086

[30] Foreign Application Priority Data Aug. 28, 1973 Primary Examiner-John J. Camby Attorney-Hill, Sherman, Meroni, Gross & Simpson [57] ABSTRACT A kiln with overlying beds for drying, burning and sintering granular and/or sludge-type material is provided with a centrally arranged vertical hollow rotatable shaft having outwardly extending raking arms thereon for distributing the material to be treated over the beds. The material to be treated is fed above the kiln into a fixed vertical pipe which extends into the upper end of a vertical distribution pipe arranged within the rotatable hollow shaft. The lower end of this vertical pipe is deflected laterally and passes through the wall of the vertical shaft and delivers the material to be treated to the uppermost bed while rotating with the hollow shaft. From the uppermost bed the material descends to the next lower beds through suitable apertures in the periphery and the center portions of the beds until it is finally discharged from the lower end of the kiln.

7 Claims, 1 Drawing Figure KILN WITH OVERLYING BEDS FOR DRYING, BURNING AND SINTERING OF GRANULAR AND/OR SLUDGE-TYPE MATERIAL The invention relates to a kiln with overlying beds, for burning, reduction or sintering of granular and/or sludge-type material which is provided with a centrally arranged hollow shaft on which raking arms are secured and which has a material feed device which supplies the material from above into the kiln.

From the German Pat. No. 1,085,550 a kiln with overlying beds is known which is used for the sintering of pyrites or the like and in which the material to be sintered is conveyed by a delivery funnel with a bucket wheel arranged in the roof of the kiln to the uppermost bed. The supply of the material takes place in this connection more or less at the periphery of this bed while the discharge of the material takes place through an opening in the central area of this bed. In the operation of the kiln the material in the first bed is engaged by the raking blades and is conveyed to the center of the bed where it drops through an inner opening to the bed located therebelow. With this known type of material delivery into the kiln, it is disadvantageous that no uniform distribution of the material takes place over the entire area of the bed, and this leads to the formation of heaps of material which without any noteworthy distribution are conveyed by the raking arms through the discharge opening. Particularly with relatively moist material it leads, with this type of material delivery, to the formation of lumps which as such are discharged from the first bed to the bed lying therebelow. This non-uniform distribution of material in the first bed is also transmitted to the bed located therebelow, and the drying-and-sintering effect by the hot gases is not sufficiently made use of in this bed as the material offers the hot gases relatively few surfaces of engagement on account of the irregularly large heaps or lump formations.

The object of the present invention is a device which makes a uniform distribution of material over the entire surface of the beds possible, particularly in the uppermost bed. In accordance with the invention the feed device is arranged above the upper end of a vertical hollow shaft and the hollow shaft is provided with one or more distributing devices which convey the material from the feed device to the bed, preferably to the uppermost bed. Since the distribution device in accordance with the invention is arranged in a hollow shaft of the raking mechanism and therefore rotates with the same, already through this arrangement a uniform circular distribution of the supplied material about the hollow shaft is attained in the first bed. The material supplied in this manner to the bed is engaged by the blades of the raking arms and is moved in the form of a spiral to the discharge opening whereby a uniform distribution of the material takes place over the entire area of the bed. Preferably, the procedure in this connection is so that with central discharge opening, the feed of the material takes place at the periphery of the bed, while with a peripheral material discharge, the material is supplied in the vicinity of the hollow shaft of the raking mechanism. Since this uniform distribution of the supplied material over the uppermost bed is also transmitted to the beds lying therebelow, not only is the heat present in the hot gases effectively utilized for the drying and sintering of the material, but also the drying and sintering effect is effectively supported in this bed and the beds lying therebelow. The kiln in accordance with the invention may therefore, as compared with known kilns of this type, be equipped with a smaller number of beds and still produce the same output.

Advantageously the distributor device comprises a central pipe passing through the vertically disposed hollow shaft of the raking device whose upper end is in connection with the material feed device and whose lower end discharges within the kiln laterally from the hollow shaft into the bed. When in this manner the distributor pipe extends through the wall of the hollow shaft of the raking device and terminates only in a bed of the kiln, the pipe is protected to a fargoing extent from the temperatures prevailing in the bed, so that particularly with very moist material to be delivered, it will not come to material baking onto the inner wall of the distributor pipe. In kilns of this type which have provisions for supplying cooling air through the hollow shaft, the distributor pipe according to the invention will be subject to a beneficial additional cooling.

In accordance with a preferred embodiment of the invention, there extends into the distributor pipe from above, a material supply pipe closed toward the top which is in connection with the gastight conveyor assembly, preferably a worm conveyor, whereby between the distributor pipe and the delivery pipe a watertight packing ring is provided. In this manner, there is produced between the material delivery device and the distributor pipe a gas-tight closure, which makes possible an operation of the kiln both under vacuum or super pressure, without danger that through the delivery device and the distributor pipe, air may escape from the kiln through this device to the outside.

In an advantageous further embodiment of the invention, the distributor pipe discharges between the raking arms of the raking device into the bed. In this manner, it is prevented that delivery material reaches the agitator arms and leads there to cakings which are often difficult to remove.

Further details, features and advantages will be disclosed in the following description of the kiln constructed in accordance with the invention and diagrammatically illustrated in the accompanying drawing.

Referring to the drawing, the kiln comprises essentially an upright stationary hollow cylindrical casing I made of fireproof material whose exterior is surrounded by sheet iron. In the cylindrical interior chamber of the kiln are located several horizontal individual beds arranged in superimposed spaced relation. In the drawing, only the uppermost beds 2 and 3 are illustrated which are provided alternatingly outwardly and inwardly with openings 4 and 5 in such manner that both the material as well as also the hot gases may travel transversely over each horizontal bed surface. Centrally in the kiln is arranged a slowly rotating raking device which consists essentially of a hollow shaft 6 and raking arms 7 extending outwardly therefrom. On the lower sides of these arms are arranged inclined raking blades 8. The top of the kiln is closed airtight by a roof 9 and two annular packings l0 and 11 arranged between the roof and the hollow shaft 6. As a sealing medium, the annular packing 10 contains sand, while the sealing medium of the annular packing 11, consists of water or sand, depending upon the pressure conditions. Between both annular packings is arranged an upwardly extending gas discharge pipe 12 whose lower end connects with the space above the uppermost bed 2.

On the roof 9 is mounted a supporting frame 13 with a bearing 14 and a material feed device. The latter comprises an upwardly inclined worm conveyor 15 which delivers the material into a vertical material supply pipe 16 closed at its upper end, while the lower end of the pipe 16 extends into a downwardly extending distributor pipe 17 which passes centrally through the hollow shaft 6 of the raking device. The lower end of the distributor pipe 17 extending laterally through the wall of the hollow shaft 6 and delivers the material onto the bed 2. Between the vertical supply pipe 16 and the larger diameter distributor pipe 17 is arranged a watertight annular packing 18. In place of the water ring packing 18 one may also provide a sand ring packing.

In operation the raking device of the kiln is set in slow rotation by means of a driving device, not shown in the drawing, while the central and upper beds are heated by endothermic processes with the assistance of suitable heating devices likewise not illustrated in the drawings. The material to be treated is delivered to the kiln by means of the worm conveyor 15 and the material supply pipe 16 to the distributor pipe 17 which latter rotates with the hollow shaft 6, from where it is laterally deflected through the wall of the hollow shaft 6 and discharged onto the bed 2. When the distributor pipe 17 rotates with the hollow shaft 6, the material is distributed uniformly on this bed in annular shape about the hollow shaft. The material is engaged by the blades 8 on the raking arms 7 and conveyed outwardly toward the periphery of the bed, where it drops through the openings 4 onto the bed 3 therebelow. On this bed 3 the material is moved by the raking blades 8 in opposition to the flow of hot gases toward the center of the bed and drops through the central opening of this bed 3 onto the bed located therebelow. This operation is repeated from bed to bed until the treated material in the kiln leaves the kiln in direction of the arrow 19 after having been cooled in the lowermost bed.

While the material travels in the prescribed manner from one bed to the next lower one in the kiln, air is supplied to the kiln according to need laterally and/or through the hollow shaft, said air together with the exhaust gases conveyed through the kiln from below and upwardly in counter-current to the material, being guided outwardly of the kiln through several pipe connections 12 arranged between the annular packings l0, 11. Since the distributing device in accordance with the invention supplies the uppermost bed with a uniform layer of the material over the entire surface of this bed, the endothermic processes provide not only in this bed a particularly good heat transfer from the hot gases to the material, but also in the beds located directly below the same, because this uniform distribution of the material in the uppermost bed is also transmitted to the lower beds. In this manner, in comparison with the kilns of this type of the prior art, not only an appreciable improvement is obtained in the predrying of the material to be treated in the uppermost beds of the kiln, but also the reduction, sintering or combustion effect is supported effectively in the other beds. Furthermore, with the distribution device in accordance with the in vention, on the one hand, by means of the material fed by the distribution pipe 17 into the bed and the annular packing 8 arranged between the material feed pipe 16 and distribution pipe 17, there is obtained to a very great advantage a gastight closure toward the outside.

so that no infiltrated air may enter from the outside through the distribution pipe to the interior of the kiln, nor may exhaust gases escape from the kiln through the 5 distribution pipe. A gas-tight closure of the kiln with respect to the atmosphere is hereby also advantageously attained through the annular packings and 11 which are arranged between the roof 9 and the hollow shaft 6. It is in this connection advisable to construct the packing 10 as sand ring packing in order to be able to receive an equalized expansion of the roof 9 during operation.

As is further apparent from the drawing, the distribution pipe 17 between the arms 7 of the raking device opens into the bed 2. In this manner, the raking arms 7 are protected against caking, particularly when supplying moist or slimy material.

The distribution device in accordance with the invention is not limited to the above indicated embodiment which is illustrated, by way of example. Thus, for example, the distribution pipe passing through the hollow shaft 6 may be constructed like trouser legs within the 1 hollow shaft 6, or be provided with a number of branch conduits which discharge into the uppermost and/or into'the beds lying therebelow. Also, the material distribution device in accordance with the invention may be used to advantage in every kiln with overlying beds, quite independently of the material to be treated and the type of operation.

What we claim is:

l. A kiln for the drying, burning, reduction and sintering of granular and/or sludge-type materials comprising:

an enclosing housing having a roof;

a plurality of vertically spaced horizontally extending beds within the housing; each of said beds having an opening therethrough for dropping material down to a lower bed;

a centrally located vertical hollow shaft extending upwardly through the beds and through the housing roof;

radially extending raking arms on the shaft for raking material on the upper surface of each of the beds;

a hollow distributor pipe extending vertically down through the shaft from the top of the shaft downwardly continuously and curving gradually laterally through the wall of the shaft opening onto the uppermost bed for distributing material while rotatand means for delivering material to the upper end of the pipe.

2. A kiln for the drying, burning, reduction and sin- 55 tering of granular and/or sludge-type materials constructed in accordance with claim 1:

wherein means are provided for generating an upward flow of air through the beds and an opening is provided above the upper bed for the release of air from the housing.

3. A kiln for the drying, burning, reduction and sintering of granular and/or sludge-type materials constructed in accordance with claim 1:

wherein the lower end of the distributor pipe is positioned circumferentially spaced from raking arms so that material is deposited on the upper bed between raking arms.

4. A kiln for the drying, burning, reduction and sintering of granular and/or sludge-type materials constructed in accordance with claim 1:

including a conveyor assembly connected with the upper end of the hollow distributor pipe;

and an annular rotational seal positioned between the conveyor and the delivery pipe.

5. A kiln for the drying, burning, reduction and sintering of granular and/or sludge-type materials constructed in accordance with claim 1:

and including two annular seals positioned between the hollow shaft and the roof of the housing.

6. A kiln for the drying, burning, reduction and sinincluding means for generating flow of air upwardly shaft.

through the hollow 

1. A kiln for the drying, burning, reduction and sintering of granular and/or sludge-type materials comprising: an enclosing housing having a roof; a plurality of vertically spaced horizontally extending beds within the housing; each of said beds having an opening therethrough for dropping material down to a lower bed; a centrally located vertical hollow shaft extending upwardly through the beds and through the housing roof; radially extending raking arms on the shaft for raking material on the upper surface of each of the beds; a hollow distributor pipe extending vertically down through the shaft from the top of the shaft downwardly continuously and curving gradually laterally through the wall of the shaft opening onto the uppermost bed for distributing material while rotating; and means for delivering material to the upper end of the pipe.
 2. A kiln for the drying, burning, reduction and sintering of granular and/or sludge-type materials constructed in accordance with claim 1: wherein means are provided for generating an upward flow of air through the beds and an opening is provided above the upper bed for the release of air from the housing.
 3. A kiln for the drying, burning, reduction and sintering of granular and/or sludge-type materials constructed in accordance with claim 1: wherein the lower end of the distributor pipe is positioned circumferentially spaced from raking arms so that material is deposited on the upper bed between raking arms.
 4. A kiln for the drying, burning, reduction and sintering of granular and/or sludge-type materials constructed in accordance with claim 1: including a conveyor assembly connected with the upper end of the hollow distributor pipe; and an annular rotational seal positioned between the conveyor and the delivery pipe.
 5. A kiln for the drying, burning, reduction and sintering of granular and/or sludge-type materials constructed in accordance with claim 1: and including two annular seals positioned between the hollow shaft and the roof of the housing.
 6. A kiln for the drying, burning, reduction and sintering of granular and/or sludge-type materials constructed in accordance with claim 1: wherein the opening through the first bed is at the outer peripheral edge thereof for the material dropping downwardly to the outer edge of the next bed therebelow, and the opening througH the next bed is the inner edge adjacent the rotary shaft.
 7. A kiln for the drying, burning, reduction and sintering of granular and/or sludge-type materials constructed in accordance with claim 1: including means for generating flow of air upwardly through the hollow shaft. 